Poured Frost Wall without Footing

[waytsh]

Has anyone else used or seen a poured concrete frost wall without a footing? I am performing a peer review where this was done on with an 8" thick concrete wall supporting 8'-16' of masonry block wall above. The walls extend about 4' into the ground and are on a crushed stone base. The wall is reinforced like a wall and not a grade beam, i.e. there are no stirrups and just uniformly distributed vertical and horizontal bars. The wall is not supporting any column loading.

Wouldn't Section 1809.4 of the IBC Code requiring a minimum footing width of 12" apply? I know something similar is commonly done is the residential industry with precast concrete panels but I have never seen it commercially.

 

[oldestguy]

Depends on what the supporting material is.

 

[Signious]

Walls without footings used to be the standard in my area, a lot of single storey 20s era houses are like that - check the width of the wall and the applied load vs. the bearing capacity of the soils.

 

[jike]

We would give the contractor the option of forming and pouring a footing and frost wall OR digging a trench by a backhoe and pouring a wall formed by the soil on either side. This "trench wall" would typically have a minimum thickness to match the formed footing width. This was done for commercial "big box" stores. Walls would typically be reinforced with two bars top and bottom.

I have never seen an 8" wall with no footing unless perhaps it was bearing on rock.

 

[emmgjld]

an 8" wide wall on grade is common in my neck of the woods. I f one does have a good handle on what the soils can support, applied loads in excess of 2000 plf should be easy to accommodate. When I am dealing with stiffer soils, structural fill or expansive clays, applied loads in excess of 4000 plf should not be out of range.

 

[Once20036]

Care to post a plan & section?

Whether or not it looks like a traditional beam with a couple bars in the top/bottom and stirrups doesn't mean it isn't a beam.
Stirrups aren't required unless the shear force exceeds 50% of the shear capacity.
If there are 2 bars in the top and 2 in the bottom, that will address the flexure - maybe the rest of the uniformly distributed (horizontal) bars are there for temp, or are skin reinforcing.
Are there columns at 20' on center such that this could behave as a beam from spread footing to spread footing?

Most geotech reports I've seen specify a minimum wall footing width, so I`d be reluctant to consider this a bearing element.

 

[waytsh]

Thank you all for the responses. Here is the requested detail.

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1530278505/tips/Frost_Wall_lbux3t.pdf[/url]